External drug pumps are typically used to deliver to patients substances which contain large molecules which cannot be digested when administered orally, such as insulin, biogenic drugs or protein drugs among others. Typically, the pump is adhered to the abdomen or chest of the patient and delivers the substance to the patient via a cannula or needle that is inserted into the patient's skin.
U.S. patent application Ser. No. 12/345,818 filed Dec. 30, 2008, and PCT Patent Application PCT/US09/69552, filed Dec. 27, 2009, to the same inventor, describe a needle assembly for administering a drug from a vial. (The terms “drug” and “substance” are used interchangeably throughout the specification and claims, and encompass any material administered to a subject. The term “vial” throughout the specification and claims encompasses any container for a drug, such as but not limited to, a cartridge, syringe, bottle, ampoule and many more, and is not limited to any size or shape.) The needle assembly includes a needle held in a needle holder, and an activation mechanism for activating delivery of the substance through the needle, such as a push button that initiates the delivery of the substance. The activation mechanism includes a safety latch that prevents the needle from pricking a person accidentally and prevents inadvertent administration of the drug. The safety latch initially impedes movement of the needle holder. When the safety latch is placed on the subject, the safety latch moves to a position that permits moving the needle holder to cause the needle to protrude outwards of the housing to pierce the subject to allow administration of the substance to the subject.
A limitation of this prior art needle assembly is that elderly, invalid or physically challenged persons may find it difficult to push the push button to activate delivery of the substance. In addition, the act of pressing the button immediately or after a period of time may be forgotten or delayed, which may adversely affect the therapeutic treatment efficiency.